Generalized thermoelasticity study in ultrashort pulsed laser machining of ceramic considering material removal and variable material properties

Abstract

Ceramic materials are widely used in engineering due to their excellent properties, but they are difficult to be machined by conventional techniques. Ultrashort pulsed laser is an applicable tool to achieve high-quality processing of these hard-brittle materials. However, the ultrashort thermalization time and complex interactions in laser processing bring great difficulty to describe thermal-mechanical responses precisely. For this purpose, we establish a model for ceramics irradiated by femtosecond pulsed laser in the context of Green-Lindsay generalized thermoelastic theory, considering the effect of material removal and temperature-dependent material properties. Thermoelastic responses and the effect of laser parameters in the machining considering material removal are obtained by means of Finite Element Method. Results show that classical thermoelastic theory underestimates thermal stresses, while G-L thermoelastic theory predicts more accurate responses. Laser parameters, including laser intensity and pulse duration, significantly affect the thermoelastic responses and the process of material removal, which indicates the necessity of laser parameter optimization for reduced thermal stresses and higher processing efficiency. Temperature-dependence of material properties must be considered, as it has pronounced influences on thermoelastic responses. This study can be used as the preparation for the structural safety design in ultrashort pulsed laser machining.